A reduction of their power consumption is demanded to increase the operating time of electronic devices. For example, a reduction of power consumption of a power amplifier is demanded, which is included in a transmitting unit of radio equipment and configured to amplify transmission signals.
Related techniques are disclosed by Japanese National Publication of International Patent Application No. 2010-508577, Japanese Laid-open Patent Publication Nos. 2012-134705, 2008-227598, 2009-253809, and 2012-015708, and Kanbe et al., “New Architecture of Envelope Tracking Power Amplifier for Base Station”, The 21st Workshop on Circuits and Systems in Karuizawa, Apr. 21-22, 2008 (non-patent document).